(set-option :proof true)
(set-option :rewriter.eq2ineq true)
(set-option :smt.arith.eager_eq_axioms false)
(set-option :smt.arith.solver 2)
(declare-fun a () Int)
(declare-fun b () String)
(declare-fun c () String)
(assert (distinct a 0))
(assert (= a (str.len b)))
(assert (= 7 (str.len c)))
(check-sat)